Thorens TP-16 Tonearm cartridge mounting issue

Recently, I have acquired a Thorens TD-160 MKI equipped with the original TP-16 tonearm and headshell. I am using Dynavector 10x5 and Grado Gold cartridges but would like to try a Reference Grado in the near future. The problem lies within the headshell of the TP-16 tonearm, as it only allows for mounting from underneath the headshell and there are no holes on the top. After close examination, it seems I can remove the lid of the headshell but there remains a top that lies just above the threaded cartridge plate. Ideally, I would like to have 2 slots located above the headshell plate for cartridge installation and adjustment, this would make installation for Grado Reference and other cartridges much easier.

Does anyone know if there are other headshells that I could fit directly on the end of a TP16 with open slots on the top? Maybe a MKII headshell would work but I am really not sure?

Here is a link to a picture of a TP16 tonearm-

Thanks to everyone for your input.

Just a note - it seems there is no headshell on the Thorens TP16 MKII, just interchangeable arm wands.
How about screwing through the cartridge body and into the tp16 tonearm sled with a longer Thorens screw..You can get the longer screws and maybe go right through the cartridge body and into the Thorens headshell sliding sled...Instead of screwing from the top,Screw in from the bottom up.....?
You wouldn't be using the screws with the Grado wood body but longer Thorens screws.......
The TP-16 was revised at least two times that I know of. Each version had a different "headshell" design. I think one version actually had a removable headshell with a bayonet-style mount, and another had the removable armwand and a more traditional-looking headshell but it still required an unusual cartridge mounting technique as there were still no slots at the top. Why Thorens designed them this way, I have no idea.

I believe the last few years of the TD160 used the TP90 tonearm, which has what you're looking for. Perhaps the armwand is interchangeable with your TP16. The problem is, Thorens parts are rare and expensive and so this might be out of your comfort level in terms of experimentation.

The easiest solution in my opinion would be to swap out the arm completely for a Rega or Jelco or something in the $300-$400 range. I've also heard that the Linn Basik Plus and Akito work pretty well on Thorens decks. And, of course, if you came across a trashed parts unit with a TP90 arm, I don't see any reason why you couldn't swap arms.